int s,v;
cin >> s >> v;
int m = 480;
m -= s * 1.0 / v  + 10;
if (m < 0)
{
    m += 1440;
}
cout << 0 << m / 60 << ":";
if (m % 60 < 10)
{
    cout << 0;
}
cout << m % 60;
return 0;